COLUMBIA  LIBRARIES  OFFSITE 


HX641 00090 
QP121  .C78  The  reialKxi  ol  the 


RECAP 


GOOT.'BS 


Ri^LATI'J.: 


n-" 


^Ij2d. 


CzL 


College  o{  ^fjpstcians  anb  g>urgeon« 


Hitjrarp 


"^r*^^   ^       ff  cr/^r/7      v. 


THE  RELATION  OP  THE  DORSAL  ROOTS  OF  THE 
SPINAL  NERVES  AND  THE  MESENCEPHALON  TO 
THE  CONTROL  OF  THE  RESPIRATORY  MOVEMENTS 


BY 


HELEN  COPELAND  COOMBS 


A  DISSERTATION 

Submitted  in  Partial  Fulfillment  of  the  Requirements  for  the  Degree 

of  Doctor  of  Philosophy  in  the  Faculty  of  Pure  Science, 

Columbia  University,  New  York  City 


Reprinted  from  The  American  Journal  of  Physiology,  Vol.  XLVI 

July,  1918 


THE  RELATION  OF  THE  DORSAL  ROOTS  OF  THE 
SPINAL  NERVES  AND  THE  MESENCEPHALON  TO 
THE  CONTROL  OF  'i  HE  RESPIRATORY  MOVEMENTS 


BY 

HELEN  COPELAND  COOMBS 


A  DISSERTATION 

Submitted  in  Partial  Fulfillment  of  the  Requirements  for  the  Degree 

of  Doctor  of  Philosophy  in  the  Faculty  of  Pure  Science, 

Columbia  University,  New  York  City 


Reprinted  from  The  American  Journal  of  Physiology,  Vol.  XLVI 

•July,  1918 


Reprinted  from  The  American  Journal  of  Phtbiology,  N'ol.  46,  No.  4, 

July.  l5l8 


THE  RELATION  OF  THE  DORvSAL  ROOTS  OF  THE  SPIXAL 
NERVES  AND  THE  MESENCEPHALON  TO  THE  CON- 
TROL OF  THE  RESPIRATORY  MOVEMENTS 

HELEN  C.  COOMBS 

From  the  Department  of  Physiologij,  Columbia  University 

Received  for  publication  May  7,  1918 

The  general  history  of  the  work  upon  the  nervous  mechanism  of 
respiration  begins  with  the  experiments  of  LeGallois  and  Flourens  in 
the  early  part  of  the  nineteenth  century.  In  1811  LeGallois  (1)  demon- 
strated that  after  transection  below  the  medulla,  all  respiratory  move- 
ments of  the  body  cease  with  the  exception  of  movements  of  the  mouth, 
which  cease  also  after  section  of  the  medulla.  Flourens  (2)  amplified 
and  confirmed  this  work  (1842-1851).  His  experimental  procedures 
began  by  removing  the  cerebrum,  then  the  cerebellum,  then  the  corpora 
quadrigemina  of  an  animal  (rabbits  and  pigeons  were  mostly  used). 
Respiration  persisted  until  sections  of  the  medulla  were  made,  then  it 
failed.  Reversing  the  operation  and  beginning  with  the  lumbar  spinal 
cord,  making  successive  sections  upward  he  found  that 

In  destroying  the  costal  spinal  cord,  the  rise  and  fall  of  the  sides  diminished 
gradually  and  when  he  had  finished,  had  entirely  disappeared. 

As  he  continued  to  make  sections  upward,  respiration  was  main- 
tained, although  with  difficulty,  by  the  diaphragm  until  the  origin  of 
the  nerves  of  the  diaphragm  was  reached  when  with  their  section  and 
consequent  cessation  of  the  movements  of  the  diaphragm,  all  effective 
respiration  stopped,  for  the  yawnings  of  the  mouth  and  glottis  which 
alone  survived  had  no  effect.  He  then  proceeded  in  a  reverse  manner, 
removing  the  medulla  by  transverse  sections  from  front  to  rear.  The 
yawning  movements  disappeared  first;  then  the  dilation  of  the  nostrils; 
the  inspiratory  movements  of  the  trunk  alone  survived  and  finally 
these  failed  also.  These  experiments  appear  to  indicate  that  the  spinal 
respiratory  nerves  are  unable  of  themselves  to  maintain  rhythmic 
respiratory  movements  but  are  dependent  on  the  action  of  a  central 
coordinating  mechanism  situated  somewhere  above  the  lower  end  of 
the  medulla  oblongata. 

459 


460  HELEN    C.    COOMBS 

Volkmann  (1842),  Longet  (1847)  and  SchifY  (1858)  (3)  showed  that 
the  central  respirator}-  mechanism  is  a  double  organ  which  can  be 
divided  by  a  median  longitudinal  section  without  causing  the  death 
of  the  animal;  and  Longet,  and  more  particularly  Schiff,  endeavored 
to  show  that  this  central  mechanism  is  located  in  the  nucleus  of  the 
grej'  matter  in  the  alae  cinereae  in  the  lower  part  of  the  bulb,  on  each 
side  beneath  the  floor  of  the  fourth  ventricle,  and  that  the  paths  by 
which  the  impulse  is  conducted  thence  to  the  spinal  cord  run  in  the 
lateral  bundles, 

Unilateral  section  of  which  at  the  lower  level  of  the  bulb,  or  at  the  level  of 
the  second  or  third  cervical  vertebrae,  suffices  to  produce  respiratory  paralysis 
on  the  same  side. 

In  opposition  to  this  view,  Brown-Sequard  (4)  enunciated  his  doc- 
trine of  "inhibitory  centers."  He  showed  in  1860  that  if  young  ani- 
mals were  kept  alive  by  artificial  respiration  for  some  time  after  section 
of  the  spinal  cord  below  the  medulla,  when  the  artificial  respiration 
was  stopped,  coordinated  movements  of  the  thorax  and  diaphragm 
might  still  be  observed  for  a  time.  He  therefore  concluded  that  the 
center  for  respiration  was  not  sharply  localized  in  the  medulla  but 
extended  throughout  the  spinal  cord.  The  effects  of  section  of  the 
spinal  cord  below  the  medulla,  he  attributed  to  "inhibition"  of  these 
centers  following  the  lesion  of  the  cord,  and  he  compared  the  phenomena 
with  those  of  spinal  shock. 

This  doctrine,  including  that  of  spinal  respiration,  was  later  pre- 
sented in  fuller  form  by  Langendorff  (1887)  and  Wertheimer  (5)  who 
observed  that  the  respiratory  muscles  of  the  trunk  could  sometimes 
be  made  to  contract  after  separation  of  the  cord  from  the  bulb  in 
animals  poisoned  with  strychnine,  in  animals  with  the  cord  artificially 
cooled  or  subjected  to  prolonged  artificial  respiration.  Wertheimer 
declared  that  such  contractions  showed  the  power  of  the  spinal  cord 
to  originate  respiratory  impulses. 

Such  an  hypothesis  has,  however,  been  too  often  refuted  to  be  at  all 
acceptable  at  the  present  time.  Schiff,  in  his  early  exposition  of 
respiratory  hemiplegia,  demonstrated  that  section  of  the  spinal  cord 
at  the  level  of  the  second  and  third  cervical  vertebrae  paralyzes  the 
respiratory  mechanism. 

Porter  (6),  in  his  study  of  the  innervation  of  the  diaphragm,  fol- 
lowed a  similar  line  of  reasoning.  He  showed  that  since  hemisections 
of  the  spinal  cord  above  the  phrenic  nuclei  do  not  inhibit  the  diaphragm 


NERVOUS   REGULATION   OF   RESPIRATION  461 

on  the  same  side,  it  follows  that  two  hemisections  altogether  separating 
the  phrenic  nuclei  from  the  bulb  do  not  inhibit  the  diaphragm  on  their 
respective  sides.  In  other  words,  the  arrest  of  thoracic  and  diaphrag- 
matic breathing  in  consequence  of  the  separation  of  the  phrenic  nuclei 
from  the  bulb  is  not  an  inhibition.  But  one  explanation  of  the  arrest 
is  then  possible;  the  phrenic  nuclei  effect  no  respiratory  discharge  after 
their  separation  from  the  bulb  because  they  receive  no  impulses  and 
cannot  originate  them.  Hence  the  cells  for  the  discharge  of  respira- 
tory impulses  are  situated  above  the  calamus  scriptorius  and  not  in 
the  spinal  cord. 

In  addition  to  this,  StarHng  (7)  has  pointed  out  that  cells  from  which 
the  nerve  fibers  go  to  the  respiratory  muscles  can,  like  the  motor  cells 
of  other  parts  of  the  organism,  be  affected  by  impulses  reaching  them 
along  various  paths.  Their  normal  activity  in  respiration  depends 
upon  impulses  from  the  medulla  but  they  c^n  also  be  affected  along 
other  tracts  derived  ultimately  from  the  posterior  roots,  at  the  same 
or  higher  levels  of  the  cord. 

Hering  (8)  has  concluded  that  after  division  of  all  the  dorsal  roots  of 
the  frog,  the  motor  cells  cannot  discharge  when  removed  from  periph- 
eral stimulation,  and  in  the  case  of  respiration,  he  is  convinced  that 

The  normal  rhythm  of  respiration  is  bound  up  with  the  integrity  of  the  ac- 
companying centripetal  nerves. 

Of  late  years,  however,  the  relative  importance  of  the  dorsal  roots  of 
the  spinal  nerves  in  the  maintenance  of  respiration  has  been  overlooked ; 
perhaps  the  refutation  of  the  ideas  of  ^'spinal  respiratory  centers"  had 
a  discouraging  effect,  certain  it  is  that  little  or  no  mention  of  the  dorsal 
roots  and  their  connection  with  respiration  is  made  in  present-day 
literature.  The  best  pronouncement  with  which  I  am  familiar  has 
been  made  by  Luciani  (9)  who  thus  epitomizes  their  activity: 

When  the  auto-regulation  by  means  of  the  vagi  is  suppressed,  an  abnormal 
type  of  respiratory  rhythm  appears  which,  although  it  provides  for  a  degree  of 
pulmonary  ventilation  sufficient  to  maintain  life,  must  yet  be  termed  dyspneic 
since  it  is  not  obtained  without  useless  expenditure  of  energy.  Under  these 
conditions  it  seems  to  us  probable  that  a  self -regulation  comes  into  play  due  to 
the  rythmical  and  alternate  excitation  of  the  sensory  paths  of  the  inspiratory 
and  expiratory  muscles. 

The  question  has  often  arisen  as  to  whether  there  is  a  mechanism 
for  the  integration  of  the  respiratory  movements  higher  than  the 
medulla.  The  opinions  of  the  various  authors  who  have  written  upon 
this  subject  appear  to  be  somewhat  divided. 


462  HELEN    C.    COOMBS 

Starling  (7),  in  citing  the  work  of  Rosenthal  and  Marckwald,  states, 

In  the  rabbit,  section  through  the  upper  part  of  the  medulla  oblongata,  sepa- 
rating the  respiratory  center  from  the  higher  parts  of  the  brain,  is  equally  with 
out  effect  on  the  depth  and  rhythm  of  the  respiratory  movements.  A  great 
change  is  observed,  however,  if  the  vagi  are  subsequently  divided  under  these 
conditions. 

Nikolaides  (10)  says  that  in  rabbits,  isolation  of  the  medulla  ob- 
longata from  above  causes  almost  the  same  effect  as  double  vagotomy. 
Luciani  (9)  states  that 

When  the  brain  is  extirpated  to  the  level  of  a  plane  which  passes  along  the 
inferior  limit  of  the  pons,  or  when  the  section  is  made  at  the  level  of  this  plane,  it 
will  be  seen  that  after  temporary  disturbance,  the  animal  continues  to  breathe 
in  a  regular,  perfectly  coordinated  manner. 

H.  Newell  Martin  (11)  found  that 

On  stimulation  of  the  mid-brain  of  the  rabbit,  close  to  the  iter  and  beneath 
the  corpora  quadrigemina,  there  is  a  respiratory  regulating  center  similar  to 
that  of  the  corpora  bigemina  of  the  frog. 

Marckwald  (5)  found  that  on  blocking  off  the  respiratory  center 
from  the  brain  above  bj  the  injection  of  parafl&n  into  the  common 
carotid,  if  these  higher  paths  are  cut  off,  the  respiration  remains  regular, 
although  deep,  and  perhaps  in  the  course  of  time  tends  to  resume  its 
original  type;  but  if  the  vagi  are  also  sectioned,  the  respiration  is 
entirely  changed;  periods  of  rapid  breathing  alternate  with  periods  of 
complete  cessation  until  the  animal  dies. 

From  the  literature  here  quoted  it  will  be  seen  that  division  of  the 
vagi,  in  connection  with  section  at  the  level  of  the  corpora  quadri- 
gemina has  been  considered.  The  possible  relationship  of  the  dorsal 
roots  of  the  spinal  nerves  has,  however,  been  given  no  attention.  I 
have  therefore  performed  a  series  of  experiments  with  a  view  to  deter- 
mining whether  there  is  a  possibility  of  such  a  relationship. 

These  experiments  have  extended  over  more  than  a  year,  and  include 
results  upon  about  forty  cats.  These  animals  were  first  etherized  and 
then  tracheotomized  and  ether  was  given  by  means  of  a  tracheal  can- 
nula. Tracings  of  both  costal  and  abdominal  respiration  were  taken 
by  means  of  Crile  stethographs  attached  to  Verdin  recording  tambours. 
I  will  consider  the  results  first  of  section  of  the  dorsal  roots  of  the  spinal 
nerves  alone,  then  at  the  level  of  the  posterior  corpora  quadrigemina 
alone  and  finally  the  effects  of  the  two  operations  together. 


NERVOUS  JiEGULATION    OF   RESPIRATION  463 

After  a  control  tracing  of  normal  respiration  (under  ether)  was  taken, 
laminectomy  was  done  and  the  dorsal  roots  of  the  spinal  nerves  were 
then  sectioned,  sometimes  in  both  thoracic  and  cervical  regions  and 
sometimes  in  the  cervical  region  only.  If  the  dorsal  spinal  roots  are 
cut  in  the  thoracic  region  alone  there  is  a  diminution  of  costal  respira- 
tion although  abdominal  respiration  remains  unaltered  and  the  rate  is 
very  little  changed;  if  the  cervical  dorsal  roots  also  are  involved,  inde- 
pendent costal  respiration  disappears,  such  costal  respiration  as  is 
present  being  passive  and  induced  by  the  abdominal  respiration  as  the 
tracing  of  March  2,  1918  (fig.  1)  shows.  Such  respiration  is  slower 
than  normal  but  the  general  character  of  the  respiratory  curve  is  not 
altered.  When  the  dorsal  roots  are  cut  in  the  cervical  region  alone, 
thoracic  respiration  is  not  greatly  changed.  An  animal  whose  dorsal 
spinal  roots  have  been  divided  aseptically  may  be  kept  ahve  for  an 
indefinite  period.  Such  an  operation,  indeed,  is  analogous  to  the  con- 
dition found  in  some  cases  of  tabes  dorsahs  in  which  the  functions 
necessary  for  the  maintenance  of  life  may  be  performed  adequately 
enough  although  precision  of  movement  is  lacking. 

It  is  of  interest  to  observe  in  connection  with  the  experimental  work 
the  remarkable  compensatory  power  of  the  individual  dorsal  roots.  If, 
for  example,  in  sectioning  the  dorsal  spinr  /  roots  in  the  thoracic  and 
cervical  regions,  a  single  root  on  either  side  be  left  intact,  costal  respira- 
tion remains  much  better  than  the  general  severity  of  the  operation 
and  the  number  of  roots  cut  would  lead  one  to  suppose  possible.  A 
study  of  the  nervous  system  impresses  one  more  and  more  with  its 
remarkable  adaptive  faciHty  in  the  rearrangement  of  channels  for  the 
conduction  of  nervous  impulses  when  the  normal  ones  are  cut  off,  and 
this  is  particularly  exemplified  in  the  conduct  of  the  dorsal  spinal  roots 
of  the  thoracic  region  of  the  cord. 

Following  is  a  protocol  of  an  experiment  in  which  the  dorsal  roots 
were  divided. 

March  2,  1918.     Male  cat  (fig.  1). 

Ether,  tracheotomy. 

Laminectomy. 

Control  tracing  of  respiration  taken  (part  1), 

Dorsal  spinal  roots  cut  from  third  cervical  to  lower  thoracic. 

Respiration  tracing  taken  (part  2). 

In  this  experiment,  the  significant  factor  is  the  complete  cessation  of 
an  active  form  of  costal  respiration,  such  shght  passive  movements  as 


464 


HELEN    C.    COOMBS 


are  present  being  the-  results  of  the  active  diaphragmatic  respiration. 
The  rate,  however,  is  not  greatly  altered. 

It  is  evident  that  in  the  maintenance  of  respiration  a  central  integrat- 
ing mechanism  is  of  first  importance.  We  are  well  aware  of  the  neces- 
sity of  the  integrity  of  the  respiratory  center  in  the  medulla  for  the 
initiation  of  respiratory  movements,  but  is  there  no  mechanism  for  the 
integration  of  nervous  impulses  concerned  with  respiration  higher  than 


imiumlimiiL 


^mpmrn'' 


mwmvmmf'^jm^] 


hWNMwmtmrnwNmmm 


-:^,MMmmtmK'"&r''!MiS! 


Fig.  1 

Part  1.     Respiration  after  laminectomy  has  been  performed. 

Part  2.     Respiration  after  section  of  the  dorsal  roots  of  the  spinal  nerves 
from  the  third  cervical  to  the  lower  thoracic.     Upper  tracing  represents  costal 
lower  abdominal  respiration. 


the  medulla?  In  other  words,  if  all  portions  of  the  brain  above  the 
medulla  were  removed,  would  respiration  proceed  in  the  same  manner 
as  before? 

In  the  technique  for  the  operation  of  section  of  the  brain  stem  above 
the  medulla,  the  carotids  were  first  tied  off  to  prevent  excessive  hemor- 
rhage and  the  animal  was  then  either  decerebrated  by  removing  the 
hemispheres  from  the  cranial  cavity  or  a  trephine  opening  was  made 


NERVOUS   REGULATION   OF   RESPIRATION  465 

over  the  occipital  ridge  and  the  corpora  quadrigemina  were  sectioned 
through  it. 

I  have  found  that  sections  in  front  of  the  corpora  quadrigemina  and 
between  the  anterior  and  posterior  corpora  produce  no  effect  upon 
respiration;  when,  however,  the  section  cuts  into  or  behind  the  pos- 
terior corpora  quadrigemina,  there  is  a  change  in  the  character  of  the 
respiration.  It  appears  to  become  slower  and  less  regular  than  the 
normal  type;  still,  it  is  hardly  of  a  gasping  character  and  maintains  a 
very  fair  type  of  ventilation. 

The  difference  in  conduct  between  the  results  of  this  operation  and 
that  of  complete  section  of  the  dorsal  roots  in  the  thoracic  and  cervical 
regions  is  one  of  degree  rather  than  kind.  In  the  latter  case,  a  few 
channels  for  sensory  impulses  may  remain  above  and  below  the  sec- 
tions— and  we  have  mentioned  the  compensatory  power  of  the  dorsal 
roots  in  this  respect — while  the  conduct  in  the  former  case  implies  a 
total  lack  of  these  sensory  impulses. 

In  this  connection,  we  cite  the  protocol  of 

March  16,  1918.    Male  cat  (fig.  2). 

Ether,  tracheotomy. 

2.00  p.m.     Normal  respiration  (part  1). 

2.45  p.m.     Carotids  tied  off,  then  section  behind  corpora  quadrigemina. 

3.30  p.m.     Good  respiration,  see  tracing  (part  2). 

Such  respiration  as  this  gives  no  indication  of  the  dyspnea  which 
some  authors  have  found  and  does,  to  some  extent,  resemble  the  slow- 
ing obtained  after  double  vagotomy.  I  have  observed  at  various 
times,  however,  that  if  after  section  is  made  there  occurs  a  hemorrhage 
into  the  fourth  ventricle,  which  causes  a  clot  producing  pressure  upon 
its  floor,  then  dyspnea  always  occurs.  But  if  no  such  hemorrhage 
occurs,  dyspnea  is  not  present  except  in  a  very  sHght  degree. 

As  I  have  previously  indicated,  the  spinal  cord  has  not  been  regarded 
as  an  important  factor  in  respiration,  during  late  years,  and  even  when 
the  possibility  of  spinal  respiratory  centers  was  under  consideration 
few  authors  ever  expressed  the  idea  of  a  relationship  between  the  dorsal 
roots  and  these  spinal  centers.  It  has  been  shown  in  a  previous  paper 
(15)  that  the  dorsal  roots  undoubtedly  play  an  important  part  in  the 
sensory  mechanism  of  costal  respiration  and  that  fibers  concerned  with 
afferent  impulses  pass  up  the  spinal  cord;  our  present  work  has  served 
to  confirm  these  findings  and  to  extend  them.  Moreover,  section  of  the 
brain  stem  at  the  level  of  the  posterior  corpora  quadrigemina  produces 


466 


HELEN   C.    COOMBS 


immediate  and  lasting  effects  upon  the  respiration.  Since  the  mesen- 
cephalon contains  afferent  and  efferent  fibers  from  the  spinal  cord,  the 
question  presents  itself  as  to  possible  relationships  between  the  dorsal 
roots  of  the  intercostals  and  the  mesencephalon  as  shown  by  the  effect 
of  section  at  the  level  of  the  posterior  corpora  quadrigemina  and  the 
dorsal  roots  of  the  spinal  nerves  in  the  cervical-thoracic  region.  Fol- 
lowing is  a  protocol  of  such  an  experiment. 


Fig.  2 

Part  1.     Normal  respiration. 

Part  2.     Respiration  after  section  behind  the  posterior  corpora  quadrigemina. 
Upper  tracing  represents  costal,  lower  abdominal  respiration. 


July  IS,  1917.     Female  cat  (fig.  3). 

Ether,  tracheotomy,  laminectomy  (part  1). 

2.40  p.m.     Carotids  tied  off. 

2.45  p.m.     Decerebration. 

2.55  p.m.     Section  behind  the  corpora  quadrigemina  (part  2). 

3.20  p.m.     Dorsal  roots  in  cervical  and  upper  thoracic  regions  cut  (part  Z). 


NERVOUS   REGULu\TION    OF   RESPIRATIOX 


467 


From  this  experiment  an  interesting  phenomenon  may  be  observed, 
namely,  that  after  section  of  the  posterior  corpora  quadrigemina,  subse- 
quent section  of  the  dorsal  roots  is  followed  by  no  additional  effects.  Such 
a  finding  leads  one  to  conclude  that  certain  of  the  sensory  impulses  at 
least,  if  not  all  connected  with  respiration  from  the  dorsal  roots  of  the 


Fig.  3 
Part  1.     Normal  respiration. 

Part  2.     Respiration  after  section  behind  the  posterior  corpora  quadrigemina 
Part  3,     Respiration  after  section  of  the  dorsal  spinal  roots  in  the   cervica 

and  upper  thoracic  regions.    Upper  tracing  represents  costal,  lower  abdomina 

respiration. 


intercostals,  pass  through  the  posterior  corpora  quadrigemina  since  the 
difference  in  severity  between  the  results  of  the  two  operations  is 
about  the  difference  that  might  be  expected  between  total  and  partial 
elimination  of  the  afferent  impulses  from  the  dorsal  roots.  ^Moreover, 
the  fact  that  section  of  the  dorsal  roots  after  section  of  the  corpora 
quadrigemina  produces  no  change  in  the  character  of  respiration  shows 
that  the  entire  effect  was  obtained  bv  the  first  division. 


468  HELEN-    C.    COOMBS 

Section  of  the  dorsal  roots  before  the  corpora  quadrigemina  are 
sectioned  does  leave  some  additional  effect  to  be  gained  by  the  latter 
operation,  as  the  following  protocol  shows. 

March  5.  1918.    Male  cat  (fig.  4). 

Ether,  tracheotomy,  laminectomy. 

2.45  p.m.     Control  tracing  ipart  1). 

3.05  p.m.  After  section  of  the  dorsal  roots  in  the  thoracic  and  lower  cervical 
regions  (part  2). 

3.30  p.m.  After  section  of  the  posterior  corpora  quadrigemina.  Note  the 
Cheyne-Stokes  respiration  (part  3). 

From  this  experiment  it  is  evident  that  there  are  still  some  afferent 
intercostal  impulses  going  through  until  the  posterior  corpora  are 
divided — not  until  then  are  all  intercostal  impulses  cut  off. 

Such  corroborative  detail  points  strongly  to  the  probabiUty  of  the 
existence  at  the  level  of  the  posterior  corpora  quadrigemina  of  some 
station  closely  related  to  the  integration  of  the  afferent  impulses  from 
the  respiratory  ''cage.'' 

While  certain  of  the  motor  impulses  concerned  in  the  skilled  move- 
ments of  respiration  must  originate  in  the  motor  areas  of  the  cerebrum 
it  is  hardly  likely  that  these  are  called  into  play  during  normal  respi- 
ration or  during  anaesthesia;  and  on  the  other  hand,  a  purely  medul- 
lary type  of  respiration  due  to  the  movements  of  the  diaphragm  alone 
is  not  normal  either.  I  beheve,  therefore,  that  sensor}'  fibers  from  the 
dorsal  roots  of  the  spinal  nerves  from  the  intercostals  travel  up  the 
brain  stem  as  high  as  the  level  of  the  posterior  corpora  quadrigemina, 
where  some  connection  with  the  descending  motor  fibers  is  effected. 
In  other  words,  the  dorsal  spinal  nerves  and  a  region  for  the  integration 
of  respiratory  impulses  at  the  level  of  the  posterior  corpora  belong  to 
the  same  system.  The  fact  that  vagi  and  mesencephalon  are  unrelated 
in  this  manner  is  what  makes  section  of  the  vagi  in  this  connection  so 
much  more  fatal  than  section  of  the  dorsal  roots — a  relation  which 
will  be  discussed  in  a  subsequent  paper. 

The  time  element  concerned  in  section  of  the  dorsal  roots  and  the 
corpora  quadrigemina  may  also  be  considered.  It  is  well  known  from 
chnical  e^-idence  that  people  in  whom  accident  or  disease  has  destroyed 
the  dorsal  spinal  nerve  roots  are  able  to  support  life  verj-  adequately. 
Stewart  (12)  has  cited  the  case  of  a  man  in  whom  all  the  ribs  became 
completely  immovable  from  disease  of  the  spine  in  the  lower  cer\'ical 
region.  He  was  able  to  lead  an  active  life  and  cany  on  his  business 
although  he  breathed  entireh'  by  means  of  the  diaphragm  and  abdom- 


NERVOUS   REGULATION    OF   RESPIRATION 


469 


inal  muscles.  Whether  an  animal  in  which  both  the  dorsal  roots  and 
the  corpora  quadrigemina  were  destroyed  could  maintain  life  very 
long,  I  am  not  prepared  to  state;  but  experimentally,  under  anaesthesia, 
good  respiration  may  be  maintained  for  several  hours  subsequent  to 
these  operations. 


Fig.  4 

Part  1.     Respiration  after  laminectomy. 

Part  2.  Respiration  after  section  of  the  dorsal  roots  in  the  thoracic  and  lower 
cervical  regions. 

Part  3.  Respiration  after  section  behind  the  posterior  corpora  quadrigemina. 
Note  the  Cheyne-Stokes  respiration.  Upper  tracing  represents  costal,  lower 
abdominal  respiration. 


Sherrington  (13),  in  his  work  on  decerebrate  rigidity,  describes  the 
persistent  tonic  spasm  which  occurs  in  certain  groups  of  muscles  after 
section  of  the  brain  stem  in  front  of  the  corpora  quadrigemina.  The 
groups  of  muscles  which  are  contracted  are  the  retractors  of  the  head 


470  HELEX    C.    COOMBS 

and  neck,  the  muscles  of  the  tail,  the  extensors  of  the  elbow,  knee, 
shoulder  and  ankle — the  antigravity  muscles.  The  spasm  depends 
on  the  integrity  of  the  dorsal  spinal  roots  and  appears  not  at  all,  or 
only  imperfectly,  in  the  limbs  of  which  the  corresponding  dorsal  nerve 
roots  are  divided.  Section  at  that  level  of  the  corpora  quadrigemina 
also  does  away  with  decerebrate  rigidity,  a  fact  which  offers  further 
confirmation  that  certain  fibers  of  the  dorsal  spinal  nerve  roots  have 
end  stations  at  this  level. 

coxcLrsioxs 

In  summarizing  the  effects  upon  the  respiratory  movements  of 
section  of  the  dorsal  roots  of  the  spinal  nerves  and  at  the  level  of  the 
posterior  corpora  quadrigemina,  my  findings  are: 

1.  Section  of  the  dorsal  roots  of  the  thoracic  and  cervical  spinal 
nerves  results  in  a  diminution  or  cessation  of  active  costal  respiration. 
The  effect  of  section  of  both  thoracic  and  cervical  nerves  is  a  more 
marked  diminution  of  costal  respiration  than  after  section  of  the 
thoracic  roots  alone.  After  section  of  the  thoracic  roots,  abdominal 
respiration  remains  unchanged  and  there  is  no  marked  alteration  in 
the  respirator^'  rate. 

2.  Section  of  the  brain  stem  below  the  anterior  corpora  quadrigemina 
results  in  a  slower,  deeper  form  of  respiration  than  normal  somewhat 
similar  to  the  most  severe  effects  which  follow  double  vagotomy. 
Abdominal  respiration  is  more  prominent  than  costal. 

3.  Section  of  the  dorsal  roots  of  the  spinal  nerves  after  section  into 
or  behind  the  posterior  corpora  ciuadrigemina  produces  no  more  severe 
effect  than  section  of  the  posterior  corpora  quadrigemina  alone. 

4.  Section  of  the  posterior  corpora  quadrigemina  subsequent  to 
section  of  the  dorsal  roots  of  the  spinal  nerves  produces  an  effect  on 
respiration  somewhat  greater  than  when  the  dorsal  roots  alone  are 
sectioned. 

o.  The  general  relationship  of  afferent  to  efferent  spinal  nerve  roots 
which  Sherrington  (14)  describes  obtains  also  in  the  afferent  and 
efferent  intercostal  roots. 

I  wish  to  express  my  thanks  to  Professor  F.  H.  Pike  of  this  department 
for  his  valuable  suggestions  and  criticisms  of  this  work. 


NERVOUS    REGULATION    OF   RESPIRATION  471 

BIBLIOGRAPHY 

(1)  LeGallois:  Experiments  sur  la  principe  de  la  vie,  160.  1824. 

(2)  Flouren's:  Recherches  experiment  ales  sur  les  proprieees  et  les  fonctions 
du  systeme  nerveux,  2d  ed.,  173,  1848. 

(3)  Rosenthal:  Hermann's  Handb.  Phj'siol.,  iv,  Leipzig.  1882. 

(4)  Browx-Sequard:  Journ.  d.  Physiol.,  1858,  i. 

(5)  Marckwald:  Zeitschr.  f.  Biol.,  1887. 

(6)  Porter:  Journ.  Physiol.,  xvii,  455. 

(7)  Starlixg:  Schiifer's  Textbook  of  physiology,  ii,  288. 

(8)  Herixg:  Arch.  f.  Physiol.,  1893,  Iviii,  614. 

(9)  LuciAXi:  Human  physiology,  i. 

LO)  NiKOLAiDEs:  Arch.  f.  Phj'siol.,  1905,  465. 

11)  Martix:  Journ.  Physiol.,  i,  370. 

12)  Stewart:  Manual  of  physiology,  6th  ed.,  223. 

L3)  Sherrixgtox:  The  integrative  action  of  the  nervous  system. 
L4)  Sherrixgtox:  Schiifer's  Textbook  of  physiology,  ii,  802. 
Pike  axd  Coombs:  This  Journal,  1917,  xlix,  395. 


VITA 

Helen  Copeland  Coombs  was  born  in  St.  Joseph,  Missouri,  July  25, 
1891.  She  graduated  from  the  Yonkers  High  School  and  entered 
Barnard  College  in  1907.  She  received  the  degree  of  Bachelor  of 
Arts  from  Barnard  College  in  1911;  the  degree  of  Bachelor  of  Science 
from  Teachers  College  in  1914;  and  of  Master  of  Arts  from  Columbia 
University  in  1915.  Since  that  time  she  has  carried  on  research  work 
in  experimental  physiology  in  the  Department  of  Physiology  of 
Columbia  University.  She  is  now  Research  Assistant  in  that 
department. 

Her  publications  are: 

The  Postural  Activity  of  the  Abdominal  Muscles   of  the  Cat.     By  F.  H.  Pike 

and  Helen  C.  Coombs.     American  J.  Physiol.,  vol.  xlii,  p.  395,  1917. 
The  Relation  of  Low  Blood  Pressure  to  a  Fatal  Termination  in  Traumatic  Shock. 

By  F.  H.  Pike  and  Helen  C.  Coombs.     Journ.  Am.  Med.  Assoc,  vol. 

Ixviii,  p.  1892,  1917. 
The  Role  of  Afferent  Impulses  in  the  Control  of  Respiratory  Movements.     By 

Helen  C.  Coombs  and  F.  H.  Pike.     Proc.  of  the  Soc.  for  Exp.  Biol,  and 

Medicine.,  vol.  xv,  p.  55,  1918. 


THE  WAVERUY  PRESS 

BALTIMORS.  U.  ■.  A. 


Date 

Due 

j             1 

1 

I 

1                               ' 

1 

'                                  i 

1 

j                   1 

1 

______'_     i         1 

:                                                                             i 

'                                      ■ 

! 

!                                                                                                             1 
1 

